You say that as if unsolicited communication is some kind of basic, elemental thing, like murder or robbery. In fact it is a deliberate exception to speech rights, which exception itself has plenty of exceptions. For instance, there doesn't seem to be much caselaw preventing junk mail, perhaps because that's the only thing keeping the USPS in operation. Keep in mind, too, that what courts may include in orders varies among jurisdictions.

One could certainly imagine a new law intended to encourage services that send automatic communications to be more careful about violating restraining orders. One could not imagine such a law actually succeeding in its stated purpose, nor could the imagination encompass such a law not having horrible follow-on effects. It's much more plausible to recall that courts may only use their injunction power to achieve equitable remedies, and that in a context of involuntary electronic messages there is nothing equitable about holding someone responsible for communications she did not create.